The tube chart is the fastest date you will get on a Fender amplifier built between 1951 and 1969 — and it is also the reason people mistake a 1990s reissue for a 1950s original. The sticker inside the cabinet carries two letters: the first is the year, the second is the month. This page is the reference version, with both cycles, the traps, and the conflicts between sources stated openly.
On the amplifier itself the sticker is the tube-location chart, present on most Fender amps made after 1950 and before 1970. If you are still looking for it, start with where the codes hide. To decode a single code, use the tube chart decoder.
Reading order: the first letter is the year
Sources disagree about the phrasing. Several shop and dealer guides describe the pair as "first letter = month, second letter = year". The published tables settle it: the alphabet is indexed on years, with A = 1951, B = 1952 and so on. The first letter is therefore the year and the second is the month, with A to L standing for January to December. We follow the tables, and every decoded result carries a worked example so you can check the logic yourself.
Vintage cycle, 1951–1969
Year letters: A = 1951, B = 1952, C = 1953, D = 1954, E = 1955, F = 1956, G = 1957, H = 1958, I = 1959, J = 1960, K = 1961, L = 1962, M = 1963, N = 1964, O = 1965, P = 1966, Q = 1967, R = 1968, S = 1969. Month letters run A = January through L = December. Worked examples: FG = July 1956, QA = January 1967.
Sources disagree about where this cycle ends. Blue Book of Guitar Values and Fender's own documentation give A to S, 1951–1969. One long-running community page extends its vintage column to T = 1970, and the ampwares tube-chart table begins its vintage column only at C and stops at Q, giving 1953–1967. Our tables use the documented 1951–1969 range, and a T is treated as disputed rather than quietly accepted.
Reissue cycle, 1990–2015
Year letters: A = 1990, B = 1991, C = 1992, D = 1993, E = 1994, F = 1995, G = 1996, H = 1997, I = 1998, J = 1999, K = 2000, L = 2001, M = 2002, N = 2003, O = 2004, P = 2005, Q = 2006, R = 2007, S = 2008, T = 2009, U = 2010, V = 2011. A second source continues the same alphabet with W = 2012, X = 2013, Y = 2014 and Z = 2015. The months are the same A–L alphabet as the vintage cycle. The documented reissue example is CG = July 1992.
Ambiguous codes, and how to resolve them
Because both cycles reuse the same letters, most codes can be read twice. CG is July — 1953 in the vintage cycle, 1992 in the reissue cycle, a 39-year gap. Our decoder returns both candidates instead of one, with the ways to separate them:
- Serial format. Late amplifiers also carry the QA date sticker on the chassis, and from 1994 Fender's own serial lookup answers directly.
- Construction and hardware. Board construction, resistor type, capacitor brands and the printing of the sticker itself separate the decades.
- Model identity. A reissue is a separate model from the original, and both exist in our Fender catalogue.
Traps that are not ambiguities
The sticker dates a batch of cabinets, not the assembly day. It was printed in runs and is found on amplifiers it was never intended for: a tweed Vibrolux carrying a 5E3 chart, or amps with a "5G12 Concert" chart. In January and February 1966 the machine stamped "OA" and "OB" instead of "PA" and "PB". And reprinted, artificially aged stickers — "doctored" charts — are a known problem in the collector market, so a sticker that looks too new for its cabinet deserves a second look.
What this means in practice
Treat the tube chart as your first witness, not your only one. Confirm it with a transformer or speaker code, which dates a part rather than a batch of cabinets, and if the two disagree treat the newer part as a replacement — the reasoning is on our methodology page. Both cycles, with per-code confidence and sources, are in the standalone decoder, and the underlying tables come from Blue Book of Guitar Values (bluebookofguitarvalues.com), Fender support, ampwares.com and superiormusic.com.